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PubMed1982

Interaction of Epstein-Barr virus with leukaemic B cells in vitro. II. Cell line establishment from prolymphocytic leukaemia and from Waldenström's macroglobulinaemia.

Leukaemic B-cell populations were prepared from six patients with high-count prolymphocytic leukaemia (PLL) as well as from one patient with Waldenström's macroglobulinaemia (WM) in frankly leukaemic phase, and their response to in vitro Epstein-Barr (EB) virus infection was monitored in terms of expression of the virus-associated nuclear antigen EBNA and of virus-induced transformation to continuous cell lines. The individual leukaemic populations, tested on several occasions, gave reproducibly different responses one from another which were not obviously related to differences either of surface immunoglobulin phenotype or of immunoglobulin secretor status in vivo. After infection, four out of six PLL populations showed either transient or a more persistent expression of EBNA, always involving a minority of the cells, with no evidence of any virus-induced transformation up to six weeks. In contrast, two out of six PLL samples as well as the WM sample rapidly gave rise to EBNA-positive cell lines which, on the evidence both of restricted immunoglobulin class expression and of abnormal marker chromosomes, were clearly derived from the leukaemic cells. Further comparative studies of such leukaemic B-cell populations may help to define host cell components necessary for the triggering of EB-virus-induced cellular transformation.

Animals↗
PubMed2002

Wavelet transforms for the characterization and detection of repeating motifs.

The role of repeating motifs in protein structures is thought to be as modular building blocks which allow an economic way of constructing complex proteins. In this work novel wavelet transform analysis techniques are used to detect and characterize repeating motifs in protein sequence and structure data, where the Kyte-Doolittle hydrophobicity scale (Eta Phi) and relative accessible surface area (rASA) data provide residue information about the protein sequence and structure, respectively. We analyze a variety of repeating protein motifs, TIM barrels, propellor blades, coiled coils and leucine-rich repeat structures. Detection and characterization of these motifs is performed using techniques based on the continuous wavelet transform (CWT). Results indicate that the wavelet transform techniques developed herein are a promising approach for the detection and characterization of repeating motifs for both structural and in some instances sequence data.

Algorithms↗
PubMed1988

Stimulation of pancreatic islet beta-cell replication by oncogenes.

Although the growth potential of the pancreatic islet beta cells is limited, glucose, cAMP, and certain polypeptide growth factors have been reported by other workers to exert modest stimulatory effects on beta-cell replication. To further assess means through which beta-cell growth can be stimulated, selected oncogene constructs linked to a rat insulin promoter were introduced by means of electroporation into free islet cells prepared from fetal rats and adult hyperglycemic obese (ob/ob) mice. The uptake and expression of the added oncogenes were sufficiently efficient to exert effects on beta-cell physiology in short-term experiments (less than or equal to 4 days). Stimulation of islet cell [3H]thymidine incorporation was observed after transfection with src alone or the combination of myc and ras. The effect observed in the fetal islet cells with src was more pronounced than any effect previously reported. Transfection with the src oncogene resulted in phosphorylation of lipocortin I and was paralleled by an increased immunofluorescence against src-like immunoreactivity in a majority of the electroporated cells. It is concluded that electroporation can induce sufficiently efficient expression of added oncogene constructs to study their effects on cells that are not readily transformable into continuously growing cell lines. Furthermore, the results suggest that beta-cell replication might be manipulated extrinsically by inserting appropriate growth-promoting genes into these cells.

Animals↗
PubMed2005

Comparison of STFT and wavelet transform methods in determining epileptic seizure activity in EEG signals for real-time application.

Electroencephalography (EEG) is widely used in clinical settings to investigate neuropathology. Since EEG signals contain a wealth of information about brain functions, there are many approaches to analyzing EEG signals with spectral techniques. In this study, the short-time Fourier transform (STFT) and wavelet transform (WT) were applied to EEG signals obtained from a normal child and from a child having an epileptic seizure. For this purpose, we developed a program using Labview software. Labview is an application development environment that uses a graphical language G, usable with an online applicable National Instruments data acquisition card. In order to obtain clinically interpretable results, frequency band activities of delta, theta, alpha and beta signals were mapped onto frequency-time axes using the STFT, and 3D WT representations were obtained using the continuous wavelet transform (CWT). Both results were compared, and it was determined that the STFT was more applicable for real-time processing of EEG signals, due to its short process time. However, the CWT still had good resolution and performance high enough for use in clinical and research settings.

Child, Preschool↗
PubMed1991

Retinoblastoma protein and simian virus 40-dependent immortalization of human fibroblasts.

Transformation and immortalization of human diploid fibroblasts by simian virus 40 (SV40) is at least a two-stage process, since transformants have a limited lifespan in culture. We have isolated immortalized derivatives (AR5 and HAL) from transformants generated with an origin-defective SV40 genome encoding a heat-labile large T protein (T antigen) and reported that both preimmortal and immortal transformants are continuously dependent on T antigen function for growth as determined by temperature shift experiments. In this study, we demonstrate complex formation between T antigen and the retinoblastoma susceptibility gene product (Rb) at 35 degrees C and observed a reduction in complexes under conditions of loss of T antigen function and growth inhibition at 39 degrees C. Viral oncogenes (polyomavirus large T protein and adenovirus E1A 12S protein) known to bind Rb were introduced into AR5 and HAL cells, both stably by gene transfer and transiently by virus vectors. Such double transformants are still unable to proliferate at 39 degrees C, although complex formation with the newly introduced oncogenes was demonstrated. We suggest that T antigen interacts with other cellular processes in addition to Rb to transform and immortalize human cells in culture. Our finding that p53-T antigen complexes are also temperature dependent in AR5 and HAL cells could provide such an additional mechanism.

Antigens, Viral, Tumor↗
PubMedDate not supplied

Conditionally immortal ovarian cell lines for investigating the influence of ovarian stroma on the estrogen sensitivity and tumorigenicity of ovarian surface epithelial cells.

The tendency of the ovarian surface epithelium (OSE) to undergo metaplastic and morphogenetic changes during the life cycle, at variance with the adjacent peritoneal mesothelial cells, suggests that its biology may be regulated by underlying ovarian stromal cues. However, little is known about the role that the ovarian stroma plays in the pathobiology of the OSE, largely because of the lack of a suitable in vitro model. Here, we describe the establishment and characterization of conditionally immortalized ovarian stromal and surface epithelial cell lines from H-2K(b)-tsA58 transgenic mice that carry the thermolabile mutant of SV-40 large T antigen under the control of an interferon-gamma (IFN-gamma)-inducible promoter. These cells express functional T antigens, grow continuously under permissive conditions at 33 degrees C in the presence of IFN-gamma, and stop dividing when the activity and expression of the tumor antigen is suppressed by restrictive conditions without IFN-gamma at 39 degrees C. Morphological, immunohistochemical, and ultrastructural analyses show that conditionally immortal OSE cells form cobblestone-like monolayers, express cytokeratin and vimentin, contain several microvilli, and develop tight junctions, whereas stromal cells are spindle-like, express vimentin but not cytokeratin, and contain rare microvilli, thus exhibiting epithelial and stromal phenotypes, respectively. At variance with the reported behavior of rat epithelial cells, conditionally immortal mouse epithelial cells are not spontaneously transformed after continuous culture in vitro. More importantly, conditioned media from stromal cells cultured under permissive conditions increase the specific activity of the endogenous estrogen receptor in BG-1 human ovarian epithelial cancer cells and promote these cells' anchorage-independent growth, suggesting the paracrine influence of a stromal factor. In addition, stromal cells cultured under restrictive conditions retain this growth-stimulatory activity, which, therefore, appears to be independent of T antigen expression. These established cell lines should provide a useful in vitro model system for studying the role of cellular interactions in OSE cell growth and tumorigenesis.

Animals↗
PubMed2004

e-Health and quality of life: the role of the Wearable Motherboard.

It is hard to place a price tag either on human life or on the quality of life. Technology is the key to enhancing the quality of life for everyone in the continuum of life from newborns to senior citizens--whether it is the safe delivery and care of undernourished premature babies, or extending the life of a senior citizen through exploratory treatments and procedures. Technology has the potential to rapidly transform healthcare and the practice of medicine by improving the quality and safety of patient care and increasing the efficiency of healthcare providers. Moreover, the healthcare industry must meet the challenge of balancing cost containment with maintenance of desired patient outcomes and this can be accomplished through the adoption of technology. Any technology that can minimize the loss of human life and/or enhance the quality of life has a value that is priceless. An overview of the key challenges facing the practice of medicine today is presented along with the need for technological solutions that can "prevent" problems. The paradigm of "e-Health" is discussed. Then, the development of the Wearable Motherboard as a "platform" for sensors and monitoring devices that can unobtrusively monitor the health and well-being of individuals (directly and/or remotely) is described. This is followed by a discussion of the applications and impact of this technology in the continuum of life--from preventing SIDS to facilitating independent living for senior citizens. Finally, the future advancements in the area of wearable, yet comfortable, systems that can continue the transformation of healthcare and e-Health to i-Health (for interactive health)--all aimed at enhancing the quality of life for humans--are presented.

Clothing↗
PubMed2006

Real-time field measurements of stable isotopes in water and CO2 by Fourier transform infrared spectrometry.

Continuous records of isotope behaviour in the environment are invaluable to understanding mass and energy fluxes. Although techniques such as isotope ratio mass spectrometry provide high precision data, they are not well suited to the analysis of a large number of samples and are currently restricted to use in the laboratory. Fourier transform infrared spectrometers are relatively cheap and sufficiently portable and robust to be taken into the field to collect continuous records of gas-phase isotope behaviour. Several examples of the application of this technique will be presented. One data set provides half-hourly determinations of vertical profiles of D/H in water vapour above agricultural fields over a 3-week period; the same infrared spectra can also be used to determine 13C/12C in CO2. The technique has also been applied to the study of CO2 in ambient air and in a limestone cave system. Some of the features and complications associated with the method will also be considered.

Agriculture↗
PubMed2006

Recommendation to treat continuous variable errors like attribute errors.

Clinical laboratory errors can be considered as either belonging to attribute or continuous variables. Attribute errors are usually considered to be pre- or post-analytical errors, whereas continuous variable errors are analytical. Goals for each error type are different. Error goals for continuous variables are often specified as limits that contain 95% of the results, whereas attribute error goals are specified as allowed error rates for serious events. This leads to a discrepancy, because for a million results, there can be up to 50,000 medically unacceptable analytical errors, but allowable pre- and post-analytical error rates are much lower than 5%. Steps to remedy this are to classify analytical error rates into severity categories, exemplified by existing glucose error grids. The results in each error grid zone are then counted, as has been recommended by the Food and Drug Administration (FDA). This in effect transforms the continuous variable errors into attribute errors. This is an improvement over current practices for analytical errors, whereby the use of uncertainty intervals is recommended that include only 95% of the results (i.e., leaves out the worst 5%), and it is precisely this 5% of results that are likely to be in the most severe zones of an error grid.

Health Planning Guidelines↗
PubMed1992

Doppler echocardiography.

In the past year, Doppler echocardiography has continued to transform the "echo laboratory" into a "cardiac imaging and hemodynamics laboratory." Evaluation of blood flow through the cardiac chambers and great vessels is moving from semiquantitative to quantitative. The potential for measuring mitral regurgitant flow more precisely has been demonstrated by evaluating the zone of flow acceleration that occurs on the left ventricular side of the mitral valve. Direct imaging of pulmonary venous return to the left atrium using transesophageal Doppler echocardiography has also allowed more precise quantification of mitral regurgitation. Left ventricular systolic function may be better quantified in patients with mitral regurgitation by calculating the ratio of the change in pressure to the change in time from the continuous wave spectrum of regurgitant flow. The practical application of transmitral flow.in evaluating diastolic function has been applied to cardiac amyloidosis.

Blood Flow Velocity↗
PubMed1978

Lymphocytes transformed by Epstein-Barr virus. Induction of nuclear antigen reactive with antibody in rheumatoid arthritis.

Sera from approximately two-thirds of patients with rheumatoid arthritis contain an antibody which is reactive with a nuclear antigen present in human B-lymphocyte tissue culture cells. The immunological reaction can be demonstrated by precipitation and immunofluorescence. Evidence is present that the reactive nuclear antigen is associated with Epstein-Barr (EB) virus-transformed lymphocytes. Normal human peripheral blood lymphocytes did not contain the nuclear antigen reactive with rheumatoid arthritis sera, but after infection with EB virus, they showed increasing amounts of reactive nuclear antigen as the cells were transformed into continuous lines. Several established human and simian lymphocyte cell lines known to carry EB viral genomes were shown to contain rheumatoid arthritis-associated nuclear antigen. Evidence is presented which suggests that the rheumatoid arthritis-associated nuclear antigen is different from the previously described EB nuclear antigen.

Antibodies↗
PubMedDate not supplied

[An analysis of isometric reflections in morphology exemplified by the mandible of the rat (Rattus, Rodentia)].

Individual, age, sex, and species differences of morphological shape is treated as a result of general shape formation process. It is assumed that mutual reflections of these differences could be described by continuous and discontinuous transformations. The first type of these reflects equilibrium properties of shape formation, while the second type reflects its non-equilibrium properties. Equilibrium process is strongly canalized and is able to generate quite limited diversity of shapes. Contrary to this, non-equilibrium process can generate a lot of different shapes, as it destroys canalized relations between characters. Idea of equilibrium process provides a background for formulation of null hypothesis about anticipated relations between characters. Statistically significant deviations from these relations allow to recognize characters that mark areas of possibly non-equilibrium transformations. Analysis of localizations of all such characters allows to formulate more meaningful hypothesis about shape transformations for a particular morphological object. Some easily available statistical methods of recognizing characters that reflect either continuous of discontinuous transformations are exposed using mandible of three rat species as an example. It is shown that discontinuous transformations are located mainly in the same areas of mandible in all modes of inter-reflections. Characters (linear measurements between morphometric landmarks) with continuous inter-reflections describe transformations of general shape of the mandible. Characters with discontinuous inter-reflections mark boundaries between functional blocks and areas with the heaviest dynamic loads.

Aging↗
PubMed1991

Synthetic oligonucleotides recreate Drosophila fushi tarazu zebra-stripe expression.

A complex array of activator and repressor elements located within 669 bp proximal to the fushi tarazu (ftz) transcriptional start site is sufficient to generate the "zebra-stripe" expression pattern characteristic of the ftz gene. P-element-mediated transformation and ftz promoter/lacZ fusion genes were used to characterize, in detail, several of these transcriptional control elements. By reconstructing promoters with synthetic oligonucleotides containing cis-regulators of stripe expression, we show that these regulatory sites can function as independent units to direct position-specific transcription in the Drosophila embryo. In particular, we demonstrate that multiple copies of a positive regulatory site can mediate expression in both the odd- and even-numbered parasegments throughout most of the germ band and that negative regulatory sites can transform a continuous pattern of gene expression into discrete stripes. The reconstructed promoter system presented provides an effective means of studying molecular mechanisms governing spatially restricted transcription in the early embryo.

Animals↗
PubMed2004

A new approach to modelling interactions between treatment and continuous covariates in clinical trials by using fractional polynomials.

We consider modelling interaction between a categoric covariate T and a continuous covariate Z in a regression model. Here T represents the two treatment arms in a parallel-group clinical trial and Z is a prognostic factor which may influence response to treatment (known as a predictive factor). Generalization to more than two treatments is straightforward. The usual approach to analysis is to categorize Z into groups according to cutpoint(s) and to analyse the interaction in a model with main effects and multiplicative terms. The cutpoint approach raises several well-known and difficult issues for the analyst. We propose an alternative approach based on fractional polynomial (FP) modelling of Z in all patients and at each level of T. Other prognostic variables can also be incorporated by first constructing a multivariable adjustment model which may contain binary covariates and FP transformations of continuous covariates other than Z. The main step involves FP modelling of Z and testing equality of regression coefficients between treatment groups in an interaction model adjusted for other covariates. Extensive experience suggests that a two-term fractional polynomial (FP2) function may describe the effect of a prognostic factor on a survival outcome quite well. In a controlled trial, this FP2 function describes the prognostic effect averaged over the treatment groups. We refit this function in each treatment group to see if there are substantial differences between groups. Allowing different parameter values for the chosen FP2 function is flexible enough to detect such differences. Within the same algorithm we can also deal with the conceptually different cases of a predefined hypothesis of interaction or searching for interactions. We demonstrate the ability of the approach to detect and display treatment/covariate interactions in two examples from controlled trials in cancer.

Age Factors↗
PubMed1991

Talent, history, and the fulfillment of promise.

Life course studies are a flourishing enterprise across the social sciences and humanities, particularly since the 1960s, but the historical roots of this work extend back at least to the turn of the century (Elder 1985; Sorensen et al. 1986). The new era is distinguished by a rapidly growing number of longitudinal samples as well as by innovative techniques for collecting and analyzing life histories. Most distinctive of the new work is its consciousness of the interplay between lives and times. To understand life trajectories one must consider the social changes underway. The events, continuities, and transformations of a changing world shape the pathways of aging. This research explores the long-term consequences of one era of social change in particular (World War II and the preceding decade of hard times) for the life experiences and career achievements of men who lived through that period. Using the data archives of the oldest longitudinal study still active in the United States (Terman 1925), we assess the career achievements of the men (born 1904-1917) in relation to cohort membership, social origins, and wartime mobilization. Through different opportunities, resources, and support, the life stage of these men in the 1930s and 40s shaped the distinctive impact of historical circumstances on their accomplishments. All of the men are members of the Stanford-Terman study, which began in 1922 with more than 800 males and has continued across 11 additional data waves up to 1986.

Aged↗
PubMed2006

Minimization method for balancing continuous prognostic variables between treatment and control groups using Kullback-Leibler divergence.

This paper proposes a method for balancing prognostic variables between treatment and control groups in design of clinical trials. It assumes that some of prognostic variables are continuous and others are categorical and that they are independently distributed. The proposed method uses the Kullback-Leibler divergence (KLD) as the index of difference in distribution between two groups. It sequentially allocates each subject to a group using a biased coin method so as to reduce the estimate of KLD. That is, when first i subjects have been allocated to two groups and the (i+1)th subject is enrolled, the KLD is estimated if the (i+1)th subject was to be allocated to either of the groups, and the subject is then allocated with a certain probability, e.g. 0.80, so as to make the KLD small. Simulation studies based on the hypothetical prognostic variables and on the actual data of hyperlipidemia patients were carried out in order to compare the proposed method with the Pocock-Simon method, which transforms the continuous prognostic variables into categorical variables by dividing the whole scale into several categories. The p values of homogeneity test of means and variances were used to evaluate the achieved balance. The observed p values in the proposed method were better than those in the Pocock-Simon method. In addition to the balance, the precision of parameter estimates assuming analysis of covariance model was examined. The results showed the precision of estimators tended to be more stable in the proposed method than the Pocock-Simon method.

Clinical Trials as Topic↗
PubMed1987

Nonpolarized secretion of truncated forms of the influenza hemagglutinin and the vesicular stomatitus virus G protein from MDCK cells.

The demonstration that the envelope glycoproteins G of vesicular stomatitus virus and hemagglutinin of influenza virus synthesized in polarized epithelial cells transfected with the corresponding genes are effectively segregated to the basolateral or apical plasma membrane domains, respectively, implies that the information determining this segregation resides within the structures of the proteins themselves. To localize the sorting information within these proteins, the polarity of secretion of truncated hemagglutinin and G glycoproteins secreted from confluent monolayers of MDCK cells transformed with vectors containing the corresponding truncated cDNAs was examined. It was found that, even though the transformed cells continued to secrete a major endogenous glycoprotein exclusively from the apical surface, the modified viral glycoproteins were secreted in a nonpolarized fashion from both sides of the monolayers. These observations suggest that important information for the sorting of the viral glycoprotein is contained within their membrane anchoring or cytoplasmic segments or that, if sorting signals are luminally located, these signals must be present in a conformation that is not attainable when the polypeptides are not attached to the membrane.

Animals↗
PubMed1988

The role of the ras oncogene in the formation of tumours.

A c-Ha-ras 1 oncogene, cloned from the EJ human bladder carcinoma cell line, was inserted into a shuttle vector carrying the selectable marker gene gpt that encodes the enzyme xanthine-guanine phosphoribosyl transferase. This construct, pSV2gptEJ, was transfected into NIH 3T3 cells by the calcium phosphate precipitation method and cells that had incorporated the plasmid were selected by growth in the presence of mycophenolic acid to which gpt confers resistance. A number of transfectant clones were tested for tumorigenicity by inoculation into nude mice. The take incidence was variable and the tumours arose only after a prolonged latent period. Many inocula produced no tumours. These results were consistent with the view that the tumours arose by selective overgrowth of minority cell populations. Cell lines were derived by explantation of these tumours and were back-selected in 2-thioxanthine, a cytotoxic analogue of the xanthine-guanine phosphoribosyl transferase substrate. Five clones were obtained that did not express detectable levels of the c-Ha-ras 1 oncogene product, p21ras. All of them showed a less-transformed morphology than the transfected NIH 3T3 cells from which they originated. Nonetheless three of these clones were found to be tumorigenic at all sites tested. This finding demonstrates that once tumorigenic variants have been selected from the ras-transformed cells, continued production of the p21ras protein is not necessary for the maintenance of tumorigenicity. Cytogenetic analysis revealed that the transfection procedure itself introduced major and stable perturbations of the genome of the transfected cells and confirmed that tumours were produced by selective overgrowth of variants with a chromosome constitution palpably different from that of the majority of the cells injected. In the light of the complex background of genomic changes produced in NIH 3T3 cells by transfection with the c-Ha-ras 1 oncogene, no conclusion can be drawn in genetic terms concerning its dominance.

Animals↗